Beckham, 33, has decided she wants to become a full-time fashion designer - and says she will never sing with her Spice Girl bandmates Mel B, Geri Halliwell, Emma Bunton and Mel C again.
Victoria - who has three children with soccer star husband David Beckham, admitted that she only agreed to a Spice reunion so that her sons Brooklyn, eight, Romeo, five, and two-year-old Cruz could see her perform.
“I was very nervous about going back into the Spice Girls because I didn’t want to send out a confused message,” she admitted to Britain’s News of The World newspaper.
“The reason I decided to do the tour was to show my kids that mummy was a pop star once.
“I’ve been thinking about this for a long time. I’m not in the music industry any more. I’m in the fashion industry.
“I’m putting together a team of people now so it will be my main project when I finish this tour in a month.
“It’s the last opportunity there will be to see the Spice Girls together.”
The other Spice Girls were quickly realized it was over without Posh Spice, and axed the extension to the reunion world tour immediately.
A statement on the Band’s website on Friday said the girls had “other commitments”.
But Victoria’s revelation comments will bring the Spice Girls’ story to a close.
It means their gig in Manchester a week ago was their final performance in the UK with their last ever concert in Toronto on February 26.
Their song Headlines (Friendship Never Ends), which only reached No 11 in the charts, will be their last single, 11 years after their debut hit Wannabe raced to No 1.
But despite deciding to call it quits early, Victoria insists she had no regrets about her time in the band.
“I like to think it was all good at the time,” she added. “But I’ll look at the pictures and think, ‘My God, look at all that bloody make-up’ or ‘Look at that hair’. So I’ll cringe a little bit. I realize that’s what made me who I am now. I’m proud of that.”
Millionaire Spice Girls boss Simon Fuller had been planning to make millions more from the reunion - which had already netted Victoria an estimated $40m.
An insider revealed: “He was desperate to keep the tour but Victoria feels she’s achieved all she can in the music industry and acknowledges that any hopes she once had about being a successful singer in her own right are long gone.”
“Fashion is far more lucrative for her. She’s actually considered a success. It gives her kudos in LA and she’s making a lot of money.”
Posh, who has already designed a range of sunglasses and her DVB-brand jeans, is predicted to rake in $30million in the next year alone.